Don't know if this has been asked before - when doing first wort hopping do I use the 60 minute boil option? I know I can chose FWH but it still requires a time in boil value. Only reason I ask is because somebody said to change that to 20 min, which I don't believe is correct. The total IBUs plummet down in that case.

Knocking the dust off this old thread.
So, I understand that BS calculates the fwh based on boil time, and this increases the total IBU count. From what I read, the bitterness perception is more mellow and balanced with fwh, so I guess what I'm looking for is an answer on IBU values after I enter fwh in BS.